"""Optional-app registry. Apps register from AppConfig.ready() — never from always-on imports."""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Callable

from django.urls import reverse


@dataclass(frozen=True)
class NavItem:
    section: str
    label: str
    url_name: str
    group: str = "Overview"
    order: int = 100


GROUP_ORDER = {
    "Overview": 10,
    "Outreach": 20,
    "Content": 30,
    "Social": 40,
    "Billing": 50,
}

_portal_nav: list[NavItem] = []
_public_nav: list[NavItem] = []
_dashboard_collectors: list[Callable] = []
_dispatchers: list[Callable] = []
_features: set[str] = set()


def register_feature(name: str) -> None:
    _features.add(name)


def enabled_features() -> frozenset[str]:
    return frozenset(_features)


def register_portal_nav(
    *,
    section: str,
    label: str,
    url_name: str,
    group: str = "Overview",
    order: int = 100,
) -> None:
    item = NavItem(
        section=section, label=label, url_name=url_name, group=group, order=order
    )
    _portal_nav.append(item)


def register_public_nav(
    *,
    section: str,
    label: str,
    url_name: str,
    order: int = 100,
) -> None:
    _public_nav.append(
        NavItem(section=section, label=label, url_name=url_name, order=order)
    )


def register_dashboard_collector(fn: Callable) -> None:
    """fn(request) -> dict merged into dashboard home context."""
    _dashboard_collectors.append(fn)


def register_dispatcher(fn: Callable) -> None:
    """fn() -> int count of items enqueued. Called by dispatch_due."""
    _dispatchers.append(fn)


def portal_nav() -> list[NavItem]:
    return sorted(
        _portal_nav,
        key=lambda i: (GROUP_ORDER.get(i.group, 99), i.order, i.label),
    )


def public_nav() -> list[NavItem]:
    return sorted(_public_nav, key=lambda i: (i.order, i.label))


def collect_dashboard_context(request) -> dict:
    extra: dict = {}
    for fn in _dashboard_collectors:
        extra.update(fn(request) or {})
    return extra


def run_dispatchers() -> int:
    total = 0
    for fn in _dispatchers:
        total += int(fn() or 0)
    return total


def reverse_nav(item: NavItem) -> str:
    return reverse(item.url_name)